STS inhibits chondrocyte IL-6 and MCP-1 secretion in a dose-dependent manner.

<p>(<b>a</b>) IL-6 and MCP-1 secretion by primed murine joint chondrocytes treated or not with 25mM STS for 1, 3 or 7 days. Values represent means±SD of triplicates from one representative experiment of three independent experiments. (<b>b</b>) qRT-PCR of IL-6 gene in primed murine chondrocytes treated or not with 25 mM STS for 3 days. (<b>c</b>) IL-6 and MCP-1 secretion by primed murine joint chondrocytes treated or not with different concentrations of STS for 3 and 7 days. Values represent means±SD of triplicates from one experiment. *<i>p</i><0.05, ** <i>p</i><0.01, *** <i>p</i><0.001, **** <i>p</i><0.0001.</p

STS inhibits murine joint chondrocytes mineralization.

<p>(<b>a</b>) Alizarin red and Von Kossa staining of murine chondrocytes treated or not (Nt) with 25mM STS for 7 days in complete BGJb. Pictures represent one representative culture well of one experiment (five independent experiments were performed). Scale bar 100μm. The graph shows Alizarin red absorbance at 405nm, expressed in % over Nt cells at 1, 3 or 7 days of culture. Values represent means±SD of triplicates from one representative experiment of three independent experiments. (<b>b</b>) Percentage of cytotoxicity in murine chondrocytes treated or not with 25mM STS for 1, 3 or 7 days. Values represent means±SD of triplicates from one representative experiment of three independent experiments. (<b>c</b>) Alizarin red staining of murine chondrocytes treated or not (Nt) with different concentrations of STS for 7 days. Pictures represent triplicates from one experiment. Scale bar 100μm. The graph shows Alizarin red absorbance at 405nm, expressed in % over Nt cells at 7 days of culture. Values represent means±SD of triplicates from one representative experiment of three independent experiments. (<b>d</b>) qRT-PCR of the indicated genes in murine chondrocytes treated or not with 25 mM STS for 7 days in complete DMEM. Values represent means±SD of triplicate samples. *<i>p</i><0.05, ** <i>p</i><0.01, *** <i>p</i><0.001, **** <i>p</i><0.0001. nd = not detectable</p

STS inhibits HA-induced ROS production and enzymes involved in cartilage degradation.

<p>ROS generation by (<b>a</b>) murine joint chondrocytes and (<b>b</b>) BMDM stimulated or not with HA crystals (500ug/ml) and treated or not with 25mM STS for 1h. Dihydroethidium (DHE) staining was used as an indicator of intracellular ROS generation. MitoSOX^™ Red reagent was used as an indicator of mitochondrial ROS generation. Values represent means±SD of triplicates from one representative experiment of two independent experiments and are expressed as %of ROS in unstimulated cells. (<b>c</b>) qRT-PCR of the indicated genes in murine chondrocytes stimulated or not with HA crystals (500ug/ml) and treated or not with 25mM STS for 30 minutes in DMEM. Values represent means±SD of triplicate samples. *<i>p</i><0.05, ** <i>p</i><0.01, *** <i>p</i><0.001, **** <i>p</i><0.0001.</p

STS inhibits formation of new calcific deposits and cartilage degradation in experimental OA.

<p>(<b>a</b>) Representative micro-CT scan images of menisectomized murine knee joints after vehicle (PBS) or STS treatment for two months after surgery. White arrows show periarticular deposits in menisectomized knees treated with vehicle and their reduction in STS treated mice. Graphs show CTAnalyzer quantitative analysis of new formation volume (mm³) and new formation crystal content (μg) in PBS- and STS-treated menisectomized mice. Data are expressed as the mean±SD (<b>b</b>) Representative histologies of PBS- and STS-treated menisectomized knees, stained with Safranin-O. Red arrows show degenerative OA changes in the articular cartilage of PBS-treated mice. Scale bars 150 μm. Graphs show tibial and femoral scoring of cartilage damage and Safranin-O loss, accordingly to OARSI method. Values represent means±SD. (<b>c</b>) Correlation graph between tibial cartilage damage score and new formation volume of pooled PBS- and STS-treated mice. (Mice number: PBS n = 20, STS n = 19).</p

STS inhibits HA-induced cytokine and chemokine selectively in chondrocytes.

<p>(<b>a</b>) IL-6 and MCP-1 secretion by primed murine joint chondrocytes and (<b>b</b>) IL-6, MCP-1, IL-1β and TNF-α secretion by primed murine BMDM, stimulated or not with HA crystals (500ug/ml) and treated or not with 25mM STS 25mM for 2, 6 and 24hrs. Values represent means±SD of triplicates from one representative experiment of three independent experiments. (<b>c</b>) IL-6 secretion by human cartilage explants was measured by ELISA. Explants were stimulated with 500μg/ml of HA crystals in presence or absence of STS 25Mm for 24 h. Matched-halves of cartilage explants are connected by a line (5 explants for patients 1, 3 for patient 2, 4 for patient 3). Values represent means±SD of triplicate samples. *<i>p</i><0.05, ** <i>p</i><0.01, *** <i>p</i><0.001, **** <i>p</i><0.0001.</p

Reassessing the safety profile of lesinurad in combination with xanthine oxidase inhibitor therapy

Introduction The rate of adverse renal events has been shown to be higher in patients treated with lesinurad plus a xanthine-oxidase inhibitor (XOI) than in patients treated only with a XOI. We reassessed the risks for various adverse renal events from a different perspective and devised a hypothesis to explain the results. Methods We used data from phase 3 trials that were publicly available from the full prescribing information document and estimated the relative risk and the number needed to treat for increased serum creatinine (sCri), renal failure, and renal lithiasis. We examined these risks for each treatment group and the risks stratified by estimated glomerular filtration rate (eGFR). Results Overall, the relative risk for sCri was > 1.0 with the 400 mg/day dose of lesinurad and higher with the 200 mg/day dose, but it was < 1.0 for both lithiasis and renal failure with the 200 mg/day dose. The relative risk was only statistically significant for sCri with the highest dose of lesinurad. When results stratified by eGFR were considered, the rates of adverse events increased with declining renal function, but the relative risks decreased in parallel, as the rate of adverse events increased much more in the placebo arm than in the active arm (200 mg/day dose). Indeed, the relative risk was only significant for the highest dose of lesinurad in patients with normal eGFR. Conclusion The rate of sCri events was higher in patients treated with both lesinurad and a XOI rather than a XOI alone. This rate was found to increase with decreasing eGFR, but as it does in for both active and placebo arms the relative risk is not different from that observed in the placebo arms in the labeled 200 mg/day dose. This may be explained by pathophysiological changes that develop in chronic kidney disease

Computed tomographic scans of the same knee showing osteoarthritis in the medial femoro-tibial compartment on a coronal reformation (A) and in the proximal tibio-fibular joint on a sagittal reformation (B).

<p>Osteoarthritic changes are consistent with multiple osteophytes (white arrows) and subchondral cysts (arrow heads). Articular calcifications are visible in the femoro-tibial compartment.</p

Distribution of calcifications within the meniscal segments.

<p>Distribution of calcifications within the menisci. Each medial or lateral meniscus was divided into anterior, middle and posterior segments for analysis.</p

Mean score of cartilage lesion of the tibial plateaus in knees with/without meniscal calcifications, hyaline cartilage calcifications and CT-assessed osteoarthritis.

<p>Mean score of cartilage lesion of the tibial plateaus in knees with/without meniscal calcifications (MC+/MC<b>−</b>), hyaline cartilage calcifications (HCC+/HCC<b>−</b>) and CT-assessed osteoarthritis (CT-OA+/CT-OA<b>−</b>). The percentage of knees is calculated out of the 29 left knees analyzed after dissection and ink staining.</p

Distribution of calcifications in the hyaline cartilage of the femoral condyles.

<p>Each condyle was divided into inner, middle and outer thirds for analysis.</p